FBI: U.S. now has one active shooter incident every three weeks

The study defines “active shooter incident” as one involving “an individual or individuals actively engaged in killing or attempting to kill people in a populated area.” An active shooter incident isn’t exactly the same thing as a mass killing, which according to a new federal definition involves at least three fatalities. Only 40 percent of the incidents in the FBI report would qualify as mass killings. (Sidebar: How sad is it that our official vocabulary of killing has grown so complex and precise in recent years?)